Over the years sensors have been developed which include transducers that possess a specific preferred orientation in relation to an electrical field, a magnetic field, or a mechanical force to be sensed. To maximize the response of the sensor, the transducer must be oriented in the direction of this field or force. Some examples of electrical or magnetic field sensors are position and proximity sensors such as Hall effect, magnetoresistor, capacitive, and inductive sensors and electrical current field sensors. Mechanical force sensors generally measure the flow or pressure of a liquid or gas, the mechanical stress or weight of an object, or the acceleration of an object. These sensors generally have a preferred orientation of the transducer to the electrical or magnetic field or to the physical force being sensed in order to maximize the sensitivity of the transducer.
Also, there may be other extraneous electrical or magnetic fields or mechanical forces in the system. The transducer may have to be oriented relative to these extraneous fields or forces in a specific direction to reduce the sensitivity of the transducer to them. This helps to eliminate sensing errors or noise caused by the movement of other objects or caused by the presence of other fields or forces.
These sensors also conventionally employ signal conditioning circuitry or a signal conditioner to amplify or otherwise condition the transducer signal. The signal conditioner is needed, for example, because the transducer signal is usually too low in magnitude to overcome noise or contains a large offset or other error signals that and in the signal conditioner and is thus effectively compensated for in the same manner as short term changes in temperature.
During the manufacturing process, both the transducer and the signal conditioner are formed on a common surface on the wafer known as the planar surface. Since components are not usually formed on top of other components, this results in transducers and signal conditioners that have a large surface area relative to the depth of the devices. The area taken up by these devices is generally measured along this planar surface. The depth of all such semiconductor devices is usually fixed by design considerations and is not relative to the number of devices.
Prior art sensors generally manufacture the signal conditioner and transducer on the same wafer and interconnect the two using conductive traces defined directly on the wafer. The prior art sensors are then installed as a single monolithic chip in the sensor. Since the transducer generally should be oriented in a specific direction relative to the field being sensed, this requires that the signal conditioner be oriented also to the field in like manner.
Also, the amount of area occupied by the transducer is much smaller than the area occupied by the signal conditioner. Orientation of both a transducer and a signal conditioner along the same plane generally produces a larger cross section for the sensor than could be achieved by orienting the transducer to the field and orienting the signal conditioner separately in whatever direction needed to realize the smallest cross section. Because the signal conditioner does not require a specific orientation in relation to the field, a much smaller cross section in relation to a specific direction of measurement can be realized by changing the orientation of the transducer and signal conditioner so they are orthogonal. This can only be accomplished if the transducer and signal conditioner are physically separated and electrically connected using some means other than the conductive traces so the transducer can be oriented to the field or force separately from the signal conditioner.